diff --git a/src/expat/lib/xmlparse.c b/src/expat/lib/xmlparse.c
index dbf5687613..974db712f4 100644
--- a/src/expat/lib/xmlparse.c
+++ b/src/expat/lib/xmlparse.c
@@ -5372,7 +5372,7 @@ reportDefault(XML_Parser parser, const ENCODING *enc,
       *eventEndPP = s;
       defaultHandler(handlerArg, dataBuf, (int)(dataPtr - (ICHAR *)dataBuf));
       *eventPP = s;
-    } while (s != end);
+    } while (s < end);
   }
   else
     defaultHandler(handlerArg, (XML_Char *)s, (int)((XML_Char *)end - (XML_Char *)s));
@@ -6174,12 +6174,15 @@ static XML_Char *
 poolAppend(STRING_POOL *pool, const ENCODING *enc,
            const char *ptr, const char *end)
 {
+  ICHAR* poolPtrPrev = NULL;
   if (!pool->ptr && !poolGrow(pool))
     return NULL;
   for (;;) {
     XmlConvert(enc, &ptr, end, (ICHAR **)&(pool->ptr), (ICHAR *)pool->end);
-    if (ptr == end)
+    /* complete or zero progress? */
+    if (ptr == end || pool->ptr == poolPtrPrev)
       break;
+    poolPtrPrev = pool->ptr;
     if (!poolGrow(pool))
       return NULL;
   }
diff --git a/src/expat/lib/xmltok.c b/src/expat/lib/xmltok.c
index c3f1c03384..a29f241cb6 100644
--- a/src/expat/lib/xmltok.c
+++ b/src/expat/lib/xmltok.c
@@ -335,7 +335,7 @@ utf8_toUtf8(const ENCODING *enc,
       if (((unsigned char)fromLim[-1] & 0xc0) != 0x80)
         break;
   }
-  for (to = *toP, from = *fromP; from != fromLim; from++, to++)
+  for (to = *toP, from = *fromP; from < fromLim; from++, to++)
     *to = *from;
   *fromP = from;
   *toP = to;
@@ -348,7 +348,7 @@ utf8_toUtf16(const ENCODING *enc,
 {
   unsigned short *to = *toP;
   const char *from = *fromP;
-  while (from != fromLim && to != toLim) {
+  while (from < fromLim && to < toLim) {
     switch (((struct normal_encoding *)enc)->type[(unsigned char)*from]) {
     case BT_LEAD2:
       *to++ = (unsigned short)(((from[0] & 0x1f) << 6) | (from[1] & 0x3f));
@@ -459,7 +459,7 @@ latin1_toUtf16(const ENCODING *enc,
                const char **fromP, const char *fromLim,
                unsigned short **toP, const unsigned short *toLim)
 {
-  while (*fromP != fromLim && *toP != toLim)
+  while (*fromP < fromLim && *toP < toLim)
     *(*toP)++ = (unsigned char)*(*fromP)++;
 }
 
@@ -492,7 +492,7 @@ ascii_toUtf8(const ENCODING *enc,
              const char **fromP, const char *fromLim,
              char **toP, const char *toLim)
 {
-  while (*fromP != fromLim && *toP != toLim)
+  while (*fromP < fromLim && *toP < toLim)
     *(*toP)++ = *(*fromP)++;
 }
 
@@ -545,8 +545,9 @@ E ## toUtf8(const ENCODING *enc, \
             const char **fromP, const char *fromLim, \
             char **toP, const char *toLim) \
 { \
-  const char *from; \
-  for (from = *fromP; from != fromLim; from += 2) { \
+  const char *from = *fromP; \
+  fromLim = from + (((fromLim - from) >> 1) << 1);  /* shrink to even */ \
+  for (; from < fromLim; from += 2) { \
     int plane; \
     unsigned char lo2; \
     unsigned char lo = GET_LO(from); \
@@ -608,11 +609,12 @@ E ## toUtf16(const ENCODING *enc, \
              const char **fromP, const char *fromLim, \
              unsigned short **toP, const unsigned short *toLim) \
 { \
+  fromLim = *fromP + (((fromLim - *fromP) >> 1) << 1);  /* shrink to even */ \
   /* Avoid copying first half only of surrogate */ \
   if (fromLim - *fromP > ((toLim - *toP) << 1) \
       && (GET_HI(fromLim - 2) & 0xF8) == 0xD8) \
     fromLim -= 2; \
-  for (; *fromP != fromLim && *toP != toLim; *fromP += 2) \
+  for (; *fromP < fromLim && *toP < toLim; *fromP += 2) \
     *(*toP)++ = (GET_HI(*fromP) << 8) | GET_LO(*fromP); \
 }
 
@@ -1332,7 +1334,7 @@ unknown_toUtf16(const ENCODING *enc,
                 unsigned short **toP, const unsigned short *toLim)
 {
   const struct unknown_encoding *uenc = AS_UNKNOWN_ENCODING(enc);
-  while (*fromP != fromLim && *toP != toLim) {
+  while (*fromP < fromLim && *toP < toLim) {
     unsigned short c = uenc->utf16[(unsigned char)**fromP];
     if (c == 0) {
       c = (unsigned short)
@@ -1507,7 +1509,7 @@ initScan(const ENCODING * const *encodingTable,
 {
   const ENCODING **encPtr;
 
-  if (ptr == end)
+  if (ptr >= end)
     return XML_TOK_NONE;
   encPtr = enc->encPtr;
   if (ptr + 1 == end) {
diff --git a/src/expat/lib/xmltok_impl.c b/src/expat/lib/xmltok_impl.c
index 9c2895b877..6c5a3ba4c0 100644
--- a/src/expat/lib/xmltok_impl.c
+++ b/src/expat/lib/xmltok_impl.c
@@ -93,13 +93,13 @@ static int PTRCALL
 PREFIX(scanComment)(const ENCODING *enc, const char *ptr,
                     const char *end, const char **nextTokPtr)
 {
-  if (ptr != end) {
+  if (ptr < end) {
     if (!CHAR_MATCHES(enc, ptr, ASCII_MINUS)) {
       *nextTokPtr = ptr;
       return XML_TOK_INVALID;
     }
     ptr += MINBPC(enc);
-    while (ptr != end) {
+    while (ptr < end) {
       switch (BYTE_TYPE(enc, ptr)) {
       INVALID_CASES(ptr, nextTokPtr)
       case BT_MINUS:
@@ -147,7 +147,7 @@ PREFIX(scanDecl)(const ENCODING *enc, const char *ptr,
     *nextTokPtr = ptr;
     return XML_TOK_INVALID;
   }
-  while (ptr != end) {
+  while (ptr < end) {
     switch (BYTE_TYPE(enc, ptr)) {
     case BT_PERCNT:
       if (ptr + MINBPC(enc) == end)
@@ -233,7 +233,7 @@ PREFIX(scanPi)(const ENCODING *enc, const char *ptr,
     *nextTokPtr = ptr;
     return XML_TOK_INVALID;
   }
-  while (ptr != end) {
+  while (ptr < end) {
     switch (BYTE_TYPE(enc, ptr)) {
     CHECK_NAME_CASES(enc, ptr, end, nextTokPtr)
     case BT_S: case BT_CR: case BT_LF:
@@ -242,7 +242,7 @@ PREFIX(scanPi)(const ENCODING *enc, const char *ptr,
         return XML_TOK_INVALID;
       }
       ptr += MINBPC(enc);
-      while (ptr != end) {
+      while (ptr < end) {
         switch (BYTE_TYPE(enc, ptr)) {
         INVALID_CASES(ptr, nextTokPtr)
         case BT_QUEST:
@@ -305,7 +305,7 @@ static int PTRCALL
 PREFIX(cdataSectionTok)(const ENCODING *enc, const char *ptr,
                         const char *end, const char **nextTokPtr)
 {
-  if (ptr == end)
+  if (ptr >= end)
     return XML_TOK_NONE;
   if (MINBPC(enc) > 1) {
     size_t n = end - ptr;
@@ -348,7 +348,7 @@ PREFIX(cdataSectionTok)(const ENCODING *enc, const char *ptr,
     ptr += MINBPC(enc);
     break;
   }
-  while (ptr != end) {
+  while (ptr < end) {
     switch (BYTE_TYPE(enc, ptr)) {
 #define LEAD_CASE(n) \
     case BT_LEAD ## n: \
@@ -391,11 +391,11 @@ PREFIX(scanEndTag)(const ENCODING *enc, const char *ptr,
     *nextTokPtr = ptr;
     return XML_TOK_INVALID;
   }
-  while (ptr != end) {
+  while (ptr < end) {
     switch (BYTE_TYPE(enc, ptr)) {
     CHECK_NAME_CASES(enc, ptr, end, nextTokPtr)
     case BT_S: case BT_CR: case BT_LF:
-      for (ptr += MINBPC(enc); ptr != end; ptr += MINBPC(enc)) {
+      for (ptr += MINBPC(enc); ptr < end; ptr += MINBPC(enc)) {
         switch (BYTE_TYPE(enc, ptr)) {
         case BT_S: case BT_CR: case BT_LF:
           break;
@@ -432,7 +432,7 @@ static int PTRCALL
 PREFIX(scanHexCharRef)(const ENCODING *enc, const char *ptr,
                        const char *end, const char **nextTokPtr)
 {
-  if (ptr != end) {
+  if (ptr < end) {
     switch (BYTE_TYPE(enc, ptr)) {
     case BT_DIGIT:
     case BT_HEX:
@@ -441,7 +441,7 @@ PREFIX(scanHexCharRef)(const ENCODING *enc, const char *ptr,
       *nextTokPtr = ptr;
       return XML_TOK_INVALID;
     }
-    for (ptr += MINBPC(enc); ptr != end; ptr += MINBPC(enc)) {
+    for (ptr += MINBPC(enc); ptr < end; ptr += MINBPC(enc)) {
       switch (BYTE_TYPE(enc, ptr)) {
       case BT_DIGIT:
       case BT_HEX:
@@ -464,7 +464,7 @@ static int PTRCALL
 PREFIX(scanCharRef)(const ENCODING *enc, const char *ptr,
                     const char *end, const char **nextTokPtr)
 {
-  if (ptr != end) {
+  if (ptr < end) {
     if (CHAR_MATCHES(enc, ptr, ASCII_x))
       return PREFIX(scanHexCharRef)(enc, ptr + MINBPC(enc), end, nextTokPtr);
     switch (BYTE_TYPE(enc, ptr)) {
@@ -474,7 +474,7 @@ PREFIX(scanCharRef)(const ENCODING *enc, const char *ptr,
       *nextTokPtr = ptr;
       return XML_TOK_INVALID;
     }
-    for (ptr += MINBPC(enc); ptr != end; ptr += MINBPC(enc)) {
+    for (ptr += MINBPC(enc); ptr < end; ptr += MINBPC(enc)) {
       switch (BYTE_TYPE(enc, ptr)) {
       case BT_DIGIT:
         break;
@@ -506,7 +506,7 @@ PREFIX(scanRef)(const ENCODING *enc, const char *ptr, const char *end,
     *nextTokPtr = ptr;
     return XML_TOK_INVALID;
   }
-  while (ptr != end) {
+  while (ptr < end) {
     switch (BYTE_TYPE(enc, ptr)) {
     CHECK_NAME_CASES(enc, ptr, end, nextTokPtr)
     case BT_SEMI:
@@ -529,7 +529,7 @@ PREFIX(scanAtts)(const ENCODING *enc, const char *ptr, const char *end,
 #ifdef XML_NS
   int hadColon = 0;
 #endif
-  while (ptr != end) {
+  while (ptr < end) {
     switch (BYTE_TYPE(enc, ptr)) {
     CHECK_NAME_CASES(enc, ptr, end, nextTokPtr)
 #ifdef XML_NS
@@ -716,7 +716,7 @@ PREFIX(scanLt)(const ENCODING *enc, const char *ptr, const char *end,
   hadColon = 0;
 #endif
   /* we have a start-tag */
-  while (ptr != end) {
+  while (ptr < end) {
     switch (BYTE_TYPE(enc, ptr)) {
     CHECK_NAME_CASES(enc, ptr, end, nextTokPtr)
 #ifdef XML_NS
@@ -740,7 +740,7 @@ PREFIX(scanLt)(const ENCODING *enc, const char *ptr, const char *end,
     case BT_S: case BT_CR: case BT_LF:
       {
         ptr += MINBPC(enc);
-        while (ptr != end) {
+        while (ptr < end) {
           switch (BYTE_TYPE(enc, ptr)) {
           CHECK_NMSTRT_CASES(enc, ptr, end, nextTokPtr)
           case BT_GT:
@@ -785,7 +785,7 @@ static int PTRCALL
 PREFIX(contentTok)(const ENCODING *enc, const char *ptr, const char *end,
                    const char **nextTokPtr)
 {
-  if (ptr == end)
+  if (ptr >= end)
     return XML_TOK_NONE;
   if (MINBPC(enc) > 1) {
     size_t n = end - ptr;
@@ -832,7 +832,7 @@ PREFIX(contentTok)(const ENCODING *enc, const char *ptr, const char *end,
     ptr += MINBPC(enc);
     break;
   }
-  while (ptr != end) {
+  while (ptr < end) {
     switch (BYTE_TYPE(enc, ptr)) {
 #define LEAD_CASE(n) \
     case BT_LEAD ## n: \
@@ -895,7 +895,7 @@ PREFIX(scanPercent)(const ENCODING *enc, const char *ptr, const char *end,
     *nextTokPtr = ptr;
     return XML_TOK_INVALID;
   }
-  while (ptr != end) {
+  while (ptr < end) {
     switch (BYTE_TYPE(enc, ptr)) {
     CHECK_NAME_CASES(enc, ptr, end, nextTokPtr)
     case BT_SEMI:
@@ -921,7 +921,7 @@ PREFIX(scanPoundName)(const ENCODING *enc, const char *ptr, const char *end,
     *nextTokPtr = ptr;
     return XML_TOK_INVALID;
   }
-  while (ptr != end) {
+  while (ptr < end) {
     switch (BYTE_TYPE(enc, ptr)) {
     CHECK_NAME_CASES(enc, ptr, end, nextTokPtr)
     case BT_CR: case BT_LF: case BT_S:
@@ -941,7 +941,7 @@ PREFIX(scanLit)(int open, const ENCODING *enc,
                 const char *ptr, const char *end,
                 const char **nextTokPtr)
 {
-  while (ptr != end) {
+  while (ptr < end) {
     int t = BYTE_TYPE(enc, ptr);
     switch (t) {
     INVALID_CASES(ptr, nextTokPtr)
@@ -973,7 +973,7 @@ PREFIX(prologTok)(const ENCODING *enc, const char *ptr, const char *end,
                   const char **nextTokPtr)
 {
   int tok;
-  if (ptr == end)
+  if (ptr >= end)
     return XML_TOK_NONE;
   if (MINBPC(enc) > 1) {
     size_t n = end - ptr;
@@ -1141,7 +1141,7 @@ PREFIX(prologTok)(const ENCODING *enc, const char *ptr, const char *end,
     *nextTokPtr = ptr;
     return XML_TOK_INVALID;
   }
-  while (ptr != end) {
+  while (ptr < end) {
     switch (BYTE_TYPE(enc, ptr)) {
     CHECK_NAME_CASES(enc, ptr, end, nextTokPtr)
     case BT_GT: case BT_RPAR: case BT_COMMA:
@@ -1204,10 +1204,10 @@ PREFIX(attributeValueTok)(const ENCODING *enc, const char *ptr,
                           const char *end, const char **nextTokPtr)
 {
   const char *start;
-  if (ptr == end)
+  if (ptr >= end)
     return XML_TOK_NONE;
   start = ptr;
-  while (ptr != end) {
+  while (ptr < end) {
     switch (BYTE_TYPE(enc, ptr)) {
 #define LEAD_CASE(n) \
     case BT_LEAD ## n: ptr += n; break;
@@ -1262,10 +1262,10 @@ PREFIX(entityValueTok)(const ENCODING *enc, const char *ptr,
                        const char *end, const char **nextTokPtr)
 {
   const char *start;
-  if (ptr == end)
+  if (ptr >= end)
     return XML_TOK_NONE;
   start = ptr;
-  while (ptr != end) {
+  while (ptr < end) {
     switch (BYTE_TYPE(enc, ptr)) {
 #define LEAD_CASE(n) \
     case BT_LEAD ## n: ptr += n; break;
@@ -1326,7 +1326,7 @@ PREFIX(ignoreSectionTok)(const ENCODING *enc, const char *ptr,
       end = ptr + n;
     }
   }
-  while (ptr != end) {
+  while (ptr < end) {
     switch (BYTE_TYPE(enc, ptr)) {
     INVALID_CASES(ptr, nextTokPtr)
     case BT_LT:
@@ -1373,7 +1373,7 @@ PREFIX(isPublicId)(const ENCODING *enc, const char *ptr, const char *end,
 {
   ptr += MINBPC(enc);
   end -= MINBPC(enc);
-  for (; ptr != end; ptr += MINBPC(enc)) {
+  for (; ptr < end; ptr += MINBPC(enc)) {
     switch (BYTE_TYPE(enc, ptr)) {
     case BT_DIGIT:
     case BT_HEX:
@@ -1760,7 +1760,7 @@ PREFIX(updatePosition)(const ENCODING *enc,
     case BT_CR:
       pos->lineNumber++;
       ptr += MINBPC(enc);
-      if (ptr != end && BYTE_TYPE(enc, ptr) == BT_LF)
+      if (ptr < end && BYTE_TYPE(enc, ptr) == BT_LF)
         ptr += MINBPC(enc);
       pos->columnNumber = (XML_Size)-1;
       break;